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#287 CMOS read error
Hi,
I get the following error when running Bochs, with an
MS-DOS ver 5 boot image. The emulator window comes up
fine, and asks me the current date and time, etc. Then
gets to the C: prompt ok.
I get the error when trying to run a program I wrote,
that does a whole lotta low level stuff, like handing
timer interrupts, keyboard interrupts, even goes into
protected mode, etc.
The error I get is:
Event type: PANIC
Device: [CMOS ]
Message: [CMOS ] unsupported cmos read, address=7070!
When I run my DOS program, it seems to freeze, and I
suspect it isn't getting timer ticks properly. So, I'm
wondering if the CMOS panic events are something to do
with it (??)
Any help would be appreciated.
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this bug, if one exists, seems to only appear when the RTC
is given an invalid address to read from. I have not
verified the validity of this bug since no image or code
sample was provided. My educated guess from what I know of
this part of the code is that it should not influence the
reception of interrupts or other functions.
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Hey,
Even I have the same problem. I have a PM boot loader for a
small OS, i am developing. The OS did not boot thru BOCHS
as it involved a old technology for switching back and forth
betweeen protected and real mode. Please refer bug-ID
601166 for full details of the bug. (The issue is the most recent
one in the io-device cattegory sorted by Bug-ID)
In order to use BOCHS I re-wrote the entire boot-loader
to boot in real-mode. However the code still had a write to
CMOS which was panciking. I "cont" the panic and BOCHS
loads the kernel properly. Now the kernel stops at a point
waiting for the TIMER INTERRUPTS to come in. Everything
stands still after that point.
Please note that the kernel behaves properly in an IBM PC
environment. No hassles.
After seeing this thread, (CMOS panic and timer interrupts)
I commented out the "CMOS write" part and tried BOCHS agian
with the new kernel. BOCHS still responds in the same way.
No Timer interrupts. Has this got anything to do with PIT and
PIT81 in BOCHS ? I see two of them in the configuration.
I will post the sources of my kernel in my Site in a week and
let you guyz know.
Thanks for any help,
Sarnath
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Hi Guys,
I got rid of the "Timer interrupt not ticking" problem,
BOCHS works for me now !!!! I am very excited now !!! :-)).
It was related to the PIC programming.
You need to mask interrupts coming in the PIC
(by writing FF into io ports 0x21 and 0xA1) before
re-programming the PIC into the new mode.
This bug does not show up in normal PC case.
I guess since the EMULATION is so fast (OR because that
the timer interrupts were programmed with a very high frequency
by the BIOS) this has happened. Anyway it was my bug and
not of BOCHS.
Thanks for your time
//
Cheers
Sarnath
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The port 0x70 now returns always 0xff without a panic. I'll close
this bug now.